Radial graded porous volumetric solar receiver is designed to match the non-uniform solar flux distribution. Based on the computed tomography and image-processing techniques, uniform and radial graded porous volumetric solar receivers are reconstructed. The 3D printing technique and suitable post processing are implemented to fabricate complex porous samples using super-alloy Inconel 718 as material. Both experimental and numerical studies are conducted to investigate the fluid flow and heat transfer processes in porous volumetric solar receivers. The results present that the 3D printed porous samples are suitable for solar thermal energy absorption and high temperature utilization. As for uniform porous receivers, porous media with small pore diameter has larger thermal efficiency because of enhanced convective heat transfer. Compared with the uniform porous receiver with highest thermal efficiency, the radial graded porous volumetric solar receiver with large pore diameter inside could further relatively increase the thermal efficiency by 4.1% while relatively decreases the flow resistance by 8.6%. The reasonable distribution of pore diameter of porous media could regulate the mass flow distribution and direct more air to the high heat flux region. Moreover, local overheating phenomenon is observed in the uniform porous receiver using air as heat transfer fluid. By applying the coupled optimization method, an optimum pore diameter distribution is determined for the radial graded porous volumetric solar receiver.

径向分级的多孔体太阳能接收器设计用于匹配不均匀的太阳通量分布。基于计算机断层扫描和图像处理技术，重建了均匀且径向渐变的多孔体太阳能接收器。使用超级合金Inconel 718作为材料，可实施3D打印技术和适当的后处理以制造复杂的多孔样品。进行了实验和数值研究，以研究多孔体积太阳能接收器中的流体流动和传热过程。结果表明，3D打印的多孔样品适用于太阳能热能吸收和高温利用。对于均匀的多孔接收器，由于增强的对流换热，具有小孔径的多孔介质具有较高的热效率。与具有最高热效率的均匀多孔接收器相比，内部具有大孔径的径向渐变多孔容积太阳能接收器可以进一步相对提高4.1％的热效率，同时相对降低8.6％的流阻。多孔介质孔径的合理分布可以调节质量流量分布，并将更多的空气引导至高热通量区域。此外，在使用空气作为传热流体的均匀多孔接收器中观察到局部过热现象。通过应用耦合优化方法，可以确定径向渐变的多孔体太阳能接收器的最佳孔径分布。内部具有大孔径的径向梯度多孔体太阳能接收器可进一步相对提高热效率4.1％，而相对降低流阻8.6％。多孔介质孔径的合理分布可以调节质量流量分布，并将更多的空气引导至高热通量区域。此外，在使用空气作为传热流体的均匀多孔接收器中观察到局部过热现象。通过应用耦合优化方法，可以确定径向渐变的多孔体太阳能接收器的最佳孔径分布。内部具有大孔径的径向梯度多孔体太阳能接收器可进一步相对提高热效率4.1％，而相对降低流阻8.6％。多孔介质孔径的合理分布可以调节质量流量分布，并将更多的空气引导至高热通量区域。此外，在使用空气作为传热流体的均匀多孔接收器中观察到局部过热现象。通过应用耦合优化方法，可以确定径向渐变的多孔体太阳能接收器的最佳孔径分布。多孔介质孔径的合理分布可以调节质量流量分布，并引导更多的空气进入高热通量区域。此外，在使用空气作为传热流体的均匀多孔接收器中观察到局部过热现象。通过应用耦合优化方法，可以确定径向渐变的多孔体太阳能接收器的最佳孔径分布。多孔介质孔径的合理分布可以调节质量流量分布，并引导更多的空气进入高热通量区域。此外，在使用空气作为传热流体的均匀多孔接收器中观察到局部过热现象。通过应用耦合优化方法，可以确定径向渐变的多孔体太阳能接收器的最佳孔径分布。